fix(08): add 'lean' after BEGIN_SRC
fix(08): add 'lean' after BEGIN_SRC

avigad/tutorial,fpvandoorn/tutorial,Hodapp87/cs6460_project,soonhokong/lean-tutorial,soonhokong/lean-tutorial,cjmazey/fork_leanprover_tutorial,leanprover/tutorial,avigad/tutorial,leanprover/tutorial,fpvandoorn/tutorial,cjmazey/fork_leanprover_tutorial,leanprover/tutorial,Hodapp87/cs6460_project,Hodapp87/cs6460_project,fpvandoorn/tutorial,soonhokong/lean-tutorial,avigad/tutorial,cjmazey/fork_leanprover_tutorial